It has been a conventional practice that a silver halide photographic material comprises a light-absorbing compound incorporated in a silver halide emulsion layer or other hydrophilic colloid layers to absorb light of a specific wavelength for the purpose of adjusting sensitivity, color temperature of light, or sensitivity balance in a multilayer color light-sensitive material, improving safelight safety, or inhibiting halation or light-fog due to static electricity.
When a silver halide photographic material comprising a hydrophilic colloid layer such as a light-sensitive silver halide emulsion layer provided on a support is imagewise exposed to light to record images on the light-sensitive silver halide emulsion layer, it is necessary to control the spectral composition of the light which is incident upon the silver halide emulsion layer to improve the photographic sensitivity. This is normally accomplished by incorporating a dye capable of absorbing light having a wavelength range which is not required by the light-sensitive silver halide emulsion layer in a hydrophilic colloid layer positioned farther from the support than the light-sensitive silver halide emulsion layer so that a filter layer is provided, whereby only light having a desired wavelength range is transmitted.
In particular a silver halide photographic material for the use in a photoengraving process, more particularly a daylight light-sensitive material, comprises a dye absorbing ultraviolet rays or visible light incorporated in a light-sensitive layer or a layer provided between the light source and the light-sensitive layer to improve the stability to safelight.
Alternatively, such a dye is incorporated in a hydrophilic colloid layer provided between the light-sensitive silver halide emulsion layer and the support to inhibit halation.
The dye which can be used for such a purpose must satisfy various requirements. For example, such a dye must be easily decolored and eluted from the silver halide photographic material upon photographic development so that stain caused by residual color after the development can be inhibited. Such a dye must not exert adverse effects such as fog and desensitization on the photographic emulsion. Such a dye also must not be diffused into other layers from the layer colored thereby. Furthermore, such a dye must have an excellent absorption spectral characteristic depending on the purpose of the light-sensitive material. Moreover, such a dye must have an excellent stability in a silver halide photographic material or solution with time without deterioration.
Efforts have been heretofore made to find dyes satisfying these requirements. Many dyes have been proposed. Examples of such dyes include pyrazoloneoxonol dyes as described in British Pat. No. 506,385, oxonol barbiturate dyes as described in U.S. Pat. No. 3,247,127, azo dyes as described in U.S. Pat. No. 2,390,707, styryl dyes as described in U.S. Pat. No. 2,255,077, hemioxanol dyes as described in British Pat. No. 584,609, melocyanine dyes as described in U.S. Pat. No. 2,493,747, cyanine dyes as described in U.S. Pat. No. 2,843,486, and methylene type benzylidene dyes as described in U.S. Pat. No. 4,420,555.
If the layer containing the above described dye serves as a filter layer or antihalation layer, it is necessary that the layer be selectively colored and the other layers not be substantially colored. If the dye colors the other layers, it not only exerts an adverse spectral effect on the other layers but also inhibits its effects of providing a filter layer or antihalation layer. Also, if a dye incorporated in a particular layer for the purpose of inhibiting irradiation is diffused into and colors the other layers, the same problems as describe above are found.
Further, in a light-sensitive material for printing, when a dye in diffused into a light-sensitive silver halide emulsion layer, a problem which influences tone variability occurs.
Generally, the term "image conversion" for printing means a step in which variable density which is continuously varied is converted into variable dot area. But the image conversion is not always carried out faithfully to a draft, and the modification in which gradiation is softened or hardened is usually carried out in the image conversion in order to meet requirements for obtaining a good texture or gloss of photography. The modification for the gradiation at step of the contact work is carried out by further increasing an exposure amount over a standard exposure At this time, the facility of modification in qradiation is called "tone variability". The modification in gradiation shows an increase of 5 to 10% in dot area over 50% of dot area due to the standard exposure That is, a 55 to 60% of dot area is obtained by the modification. Accordingly, it is desired that the modification is carried out in an exposure amount of about from three to five times as large as standard exposure. That is, if the tone is varied by small variation of an exposure amount, a control of the modification is difficult, and if the tone is varied by large variation of an exposure amount, the time for the modification is long.
It has heretofore been known to localize a so called acidic dye containing sulfo group or carboxy group in a particular layer by means of a mordant in order to solve these problems.
Examples of such a mordant which has been proposed include ethylenically unsaturated compound polymers containing a dialkylaminoalkylester residual group as described in British Pat. No. 685,475, products of a reaction of polyvinylalkyl ketone with aminoguanidine as described in British Pat. No. 850,281, and a vinylpyridine polymer and vinylpyridinium cation polymer as described in U.S. Pat. Nos. 2,548,564, 2,484,430, 3,148,061, and 3,756,814. In order to effectively mordant the above described acidic dye, a cationic mordant containing secondary and tertiary amino groups, a nitrogen-containing heterocyclic group, and a quaternary cationic group thereof in a polymer is used.
However, such a cationic mordant is disadvantageous in that it causes static interaction with gelatin commonly used as a hydrophilic colloid and a surface active agent containing an alcoholate group, carboxylate group, sulfonate group, or sulfate group commonly used as a coating aid, thereby deteriorating the coating properties.
Such a cationic mordant is also disadvantageous in that when it is used in a color light-sensitive material, it may deteriorate desilverability or lower the sensitivity of adjusting the emulsion layer.
It has been proposed to use a large amount of such a mordant to prevent the above described acidic dye from diffusing into the other layers. However, this approach is disadvantageous in that it is impossible to fully inhibit such diffusion and the layer in which the dye is incorporated must be thick, resulting in poor sharpness.
Furthermore, it is a common practice in the art that a light-sensitive material for the use in making photoengraving is subjected to reduction with a reducing solution to adjust density and gradation. This reducing solution contains a water-soluble iron complex as a reducing agent. Therefore, if the above described cationic mordant is used in the light-sensitive material, it is statically bonded to the iron complex, and this iron complex causes a yellow stain.